On 2016-02-09, Ignoramus4548 wrote:
After a couple of decades using UPSes, I became unconvinced that UPSes
increase reliability and especially uptime. The problem is that UPSes
fail for spurious reasons, and when they fail, they leave devices
unpowered.

An increasing number of my computers and disk arrays come with
dual power supplies (a single one will operate the equipment), so one
power supply is connected to the UPS (a 2 KVA BEST Ferrups running from
four 12V gel cells in series), and the other to the wall power, so a
short duration of outage on either is no problem. Unfortunately, some
of the older computers are single power supply so are vulnerable.

The UPS is rated for 55 AH batteries, and the last set I had in
there turn out to be 75 AH, so I got really good long-time backup, while
the UPS was claiming for a long time that I had only 15 minutes left.

Unfortunately, I let them go too long. They should be changed
out every four years, and these went in in 2009, so I had a failure when
I *reduced* the load on the UPS (it had been complaining that it could not
power the full load for a few months and thus was switched to "Line
Condition" mode (a big Ferro-resonant transformer with no backup), and
during that time the batteries fully discharged. So -- after reducing
the load, when I switched it back to "Auto", it collapsed, and did not
even have enough voltage to enable the control panel to switch back to
"line Condition" again.

The previous set of batteries came from a hamfest (a vendor who
had some that had been sitting on the shelf too long to guarantee), for
$40.00 each. I haven't seen him for the last several years, or I would
have gotten a new set. I'm now waiting for delivery of an ordered
set.( *Expensive* at new price. :-( )

Enjoy,
DoN.

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